Magnetic recording medium for magnetic encoder

Abstract

A magnetic recording medium for a magnetic encoder which has an alumite magnetic film that magnetic metal is precipitated in pores of porous aluminum oxide film so that the diameter of the pore is 80 to 200 Angstroms and the depth thereof is 3 to 100 microns. Thus, the magnetic recording medium can magnetically record in a high density and can be fabricated inexpensively.

What is claimed is: 
     
       1. A magnetic recording medium for a magnetic encoder comprising: an alumite magnetic film having pores, each of said pores having a diameter in the range of about 80 to 200 Angstroms and a depth in the range of about 10 to 100 microns; and   precipitated magnetic metal contained in said pores in an amount of 0.5 mg or more per/cm2, said magnetic metal being selected from the group consisting of iron, cobalt nickel, and their alloys.   
     
     
       2. A magnetic recording medium according to claim 1, wherein the weight of said magnetic metal is approximately from 1 to 3 mg per 1 cm 2 . 
     
     
       3. A magnetic recording medium according to claim 1, wherein: the weight of said magnetic metal is at least about 0.7 mg per 1 cm 2 .   
     
     
       4. A magnetic recording medium for use in a vertical magnetic recording system, comprising: a drum;   a porous aluminum oxide film on a peripheral surface of said drum, pores of said film extending perpendicularly to said surface, said pores having a diameter in the range of about 80 to 200 Angstroms and a depth in the range of about 10 to 100 microns and containing at least 0.5 mg per cm 2  of precipitated magnetic metal, wherein a vertical anisotropy is achieved.   
     
     
       5. A magnetic encoder according to claim 1, wherein said metal is selected from the group consisting of iron, cobalt, nickel and their alloys.